Czeckia is in the EU customs union and therefore for the purposes of land-locked or not land-locked, Czeckia has ports at its disposal. In fact Czeckia can use

Czeckia is in the EU customs union and therefore for the purposes of land-locked or not land-locked, Czeckia has ports at its disposal. In fact Czeckia can use Gdańsk without penalty. The reason landlocked countries have lower GDP is that they have to negotiate trade agreements at a disadvantage with small numbers of neighbours rather than just shipping goods to the whole world over the seas.